possible deadlock in ext4_evict_inode

Status: upstream: reported on 2025/11/07 03:25
Reported-by: syzbot+5135ee32614ae9e41ee0@syzkaller.appspotmail.com
First crash: 261d, last: 17d
Similar bugs (12)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in ext4_evict_inode (2) ext4 4 18 1227d 1404d 0/29 auto-obsoleted due to no activity on 2023/07/14 13:24
linux-6.1 possible deadlock in ext4_evict_inode (4) origin:lts-only 4 C 49 2d08h 245d 0/3 upstream: reported C repro on 2025/11/22 18:47
linux-6.1 possible deadlock in ext4_evict_inode (3) 4 1 844d 844d 0/3 auto-obsoleted due to no activity on 2024/07/12 10:45
upstream possible deadlock in ext4_evict_inode (4) ext4 4 3 384d 384d 0/29 auto-obsoleted due to no activity on 2025/10/15 00:50
upstream possible deadlock in ext4_evict_inode (5) prio:high ext4 4 C error 550 4d01h 263d 0/29 upstream: reported C repro on 2025/11/05 11:40
linux-5.15 possible deadlock in ext4_evict_inode (2) 4 2 865d 870d 0/3 auto-obsoleted due to no activity on 2024/06/20 13:51
upstream possible deadlock in ext4_evict_inode (3) ext4 4 5 698d 891d 0/29 auto-obsoleted due to no activity on 2024/12/05 07:55
linux-5.15 possible deadlock in ext4_evict_inode (3) 4 57 12d 242d 0/3 upstream: reported on 2025/11/26 09:11
upstream possible deadlock in ext4_evict_inode ext4 4 syz error error 38 2841d 2879d 15/29 fixed on 2020/05/22 17:31
linux-6.1 possible deadlock in ext4_evict_inode 4 2 1111d 1220d 0/3 auto-obsoleted due to no activity on 2023/10/19 10:40
linux-6.1 possible deadlock in ext4_evict_inode (2) 4 1 963d 963d 0/3 auto-obsoleted due to no activity on 2024/03/15 02:58
linux-5.15 possible deadlock in ext4_evict_inode 4 2 1212d 1216d 0/3 auto-obsoleted due to no activity on 2023/07/30 00:10

Sample crash report:
EXT4-fs (loop4): mounted filesystem 76b65be2-f6da-4727-8c75-0525a5b65a09 r/w without journal. Quota mode: writeback.
ext4 filesystem being mounted at /406/file1 supports timestamps until 2038-01-19 (0x7fffffff)
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.2551/15588 is trying to acquire lock:
ffff88807910c608 (sb_internal){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1633 [inline]
ffff88807910c608 (sb_internal){.+.+}-{0:0}, at: sb_start_intwrite include/linux/fs.h:1755 [inline]
ffff88807910c608 (sb_internal){.+.+}-{0:0}, at: ext4_evict_inode+0x2b4/0xe70 fs/ext4/inode.c:215

but task is already holding lock:
ffff88807910ec58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_write fs/ext4/ext4.h:1780 [inline]
ffff88807910ec58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x313/0x1060 fs/ext4/migrate.c:438

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&sbi->s_writepages_rwsem){++++}-{0:0}:
       percpu_down_read+0x44/0x1a0 include/linux/percpu-rwsem.h:51
       ext4_writepages_down_read fs/ext4/ext4.h:1768 [inline]
       ext4_writepages+0x1a4/0x350 fs/ext4/inode.c:2808
       do_writepages+0x351/0x590 mm/page-writeback.c:2575
       __writeback_single_inode+0x14e/0xee0 fs/fs-writeback.c:1635
       writeback_single_inode+0x21f/0x760 fs/fs-writeback.c:1756
       write_inode_now+0x183/0x210 fs/fs-writeback.c:2808
       iput_final fs/inode.c:1807 [inline]
       iput+0x58f/0x900 fs/inode.c:1846
       ext4_xattr_block_set+0x248b/0x2fe0 fs/ext4/xattr.c:2201
       ext4_xattr_move_to_block fs/ext4/xattr.c:2666 [inline]
       ext4_xattr_make_inode_space fs/ext4/xattr.c:2741 [inline]
       ext4_expand_extra_isize_ea+0x128f/0x1e70 fs/ext4/xattr.c:2829
       __ext4_expand_extra_isize+0x306/0x400 fs/ext4/inode.c:5990
       ext4_try_to_expand_extra_isize fs/ext4/inode.c:6033 [inline]
       __ext4_mark_inode_dirty+0x458/0x6d0 fs/ext4/inode.c:6111
       ext4_evict_inode+0x7dd/0xe70 fs/ext4/inode.c:254
       evict+0x4b7/0x8a0 fs/inode.c:705
       ext4_orphan_cleanup+0xc33/0x1470 fs/ext4/orphan.c:472
       __ext4_fill_super fs/ext4/super.c:5621 [inline]
       ext4_fill_super+0x5fb5/0x6870 fs/ext4/super.c:5744
       get_tree_bdev+0x3e5/0x520 fs/super.c:1591
       vfs_get_tree+0x8c/0x280 fs/super.c:1764
       do_new_mount+0x24a/0xa40 fs/namespace.c:3386
       do_mount fs/namespace.c:3726 [inline]
       __do_sys_mount fs/namespace.c:3935 [inline]
       __se_sys_mount+0x2e7/0x3d0 fs/namespace.c:3912
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (sb_internal){.+.+}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x37ef/0x7d80 kernel/locking/lockdep.c:5137
       lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
       percpu_down_read+0x44/0x1a0 include/linux/percpu-rwsem.h:51
       __sb_start_write include/linux/fs.h:1633 [inline]
       sb_start_intwrite include/linux/fs.h:1755 [inline]
       ext4_evict_inode+0x2b4/0xe70 fs/ext4/inode.c:215
       evict+0x4b7/0x8a0 fs/inode.c:705
       ext4_ext_migrate+0xcd4/0x1060 fs/ext4/migrate.c:588
       __ext4_ioctl fs/ext4/ioctl.c:1412 [inline]
       ext4_ioctl+0x1ede/0x3b70 fs/ext4/ioctl.c:1630
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:871 [inline]
       __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&sbi->s_writepages_rwsem);
                               lock(sb_internal);
                               lock(&sbi->s_writepages_rwsem);
  rlock(sb_internal);

 *** DEADLOCK ***

3 locks held by syz.4.2551/15588:
 #0: ffff88807910c418 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x63/0x200 fs/namespace.c:456
 #1: ffff88805bb2a210 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #1: ffff88805bb2a210 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: __ext4_ioctl fs/ext4/ioctl.c:1411 [inline]
 #1: ffff88805bb2a210 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: ext4_ioctl+0x1ed6/0x3b70 fs/ext4/ioctl.c:1630
 #2: ffff88807910ec58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_write fs/ext4/ext4.h:1780 [inline]
 #2: ffff88807910ec58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x313/0x1060 fs/ext4/migrate.c:438

stack backtrace:
CPU: 0 PID: 15588 Comm: syz.4.2551 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 check_noncircular+0x2fc/0x400 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x37ef/0x7d80 kernel/locking/lockdep.c:5137
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
 percpu_down_read+0x44/0x1a0 include/linux/percpu-rwsem.h:51
 __sb_start_write include/linux/fs.h:1633 [inline]
 sb_start_intwrite include/linux/fs.h:1755 [inline]
 ext4_evict_inode+0x2b4/0xe70 fs/ext4/inode.c:215
 evict+0x4b7/0x8a0 fs/inode.c:705
 ext4_ext_migrate+0xcd4/0x1060 fs/ext4/migrate.c:588
 __ext4_ioctl fs/ext4/ioctl.c:1412 [inline]
 ext4_ioctl+0x1ede/0x3b70 fs/ext4/ioctl.c:1630
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f8e1a19de59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f8e183f6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f8e1a425fa0 RCX: 00007f8e1a19de59
RDX: 0000000000000000 RSI: 0000000000006609 RDI: 0000000000000005
RBP: 00007f8e1a233e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8e1a426038 R14: 00007f8e1a425fa0 R15: 00007ffe4be73f98
 </TASK>

Crashes (21):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/09 06:05 linux-6.6.y da47cbc25466 b9f1ceaa .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2026/07/02 03:09 linux-6.6.y d1cfde2d5d15 27192279 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2026/06/28 00:23 linux-6.6.y d1cfde2d5d15 fb92f11c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2026/06/18 16:50 linux-6.6.y 924b4a879cbb a776b0d0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2026/06/18 16:47 linux-6.6.y 924b4a879cbb a776b0d0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2026/06/18 16:42 linux-6.6.y 924b4a879cbb a776b0d0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2026/05/13 07:49 linux-6.6.y 3b9f64db0496 a0949470 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2026/05/13 01:20 linux-6.6.y 3b9f64db0496 a0949470 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2026/02/24 04:12 linux-6.6.y 7a137e9bfa0e 41d2fa6a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2026/02/11 22:45 linux-6.6.y 1b4ef5214f17 75707236 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2026/02/09 10:23 linux-6.6.y c56aaf1a85ae 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2026/01/06 13:15 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2025/12/29 04:44 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2025/12/23 19:58 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2025/12/21 16:59 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2025/12/03 17:28 linux-6.6.y 4791134e4aeb d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2025/12/02 15:10 linux-6.6.y 4791134e4aeb d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2025/11/30 20:17 linux-6.6.y 1e89a1be4fe9 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2025/11/30 20:04 linux-6.6.y 1e89a1be4fe9 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2025/11/12 09:13 linux-6.6.y 0a805b6ea8cd 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
2025/11/07 03:25 linux-6.6.y 0a805b6ea8cd 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ext4_evict_inode
* Struck through repros no longer work on HEAD.